Geometry

1. Geometry Lesson 1-1 Points, Lines, and Planes

2. Objectives • TLW identify and model points, lines, and planes. • TLW identify collinear and coplanar points and intersecting lines and planes in space.

3. Points, lines, and Planes • Point: A point is simply a location. It is drawn as dot. A point is named using a capital letter such as the example below. The point below is point P. • A point has neither shape nor size. P

4. Points, lines, and Planes(cont’d) • Line: A line is made up of points and has no thickness or width. Points on the same line are said to be collinear. Arrowheads at both ends indicate a line, as in line AB or AB. • A line is named by using two points on the line or a lowercase script letter. The above line can be named as follows: line h, line AB or AB. • There is exactly one line through any two points. h B A

5. Points, lines, and Planes(cont’d) • Plane: A plane is a flat surface made up of points. Points that lie in the same plane are said to be coplanar. A plane is drawn as a shaded, slanted 4-sided figure. • A plane is named using a capital script letter or three noncollinear points. The above plane can be named planeF or plane ABC. • There is exactly one plane through any three noncollinear points. A B C F

6. Points, lines, and Planes(cont’d) • A point has no dimension. • A line is one-dimensional. • A square has two dimensions (length and width). • A cube has three dimensions. • Lines intersect at a point. • Planes intersect at a line. • In geometry, points, lines, and planes are considered undefined terms because they are only explained using examples and descriptions.

7. Points, Lines, and Planes in Space. • Space: Space is a boundless, three-dimensional set of all points. Points, lines, and planes are contained in space. A D B C F E G H P There are six planes in the figure above. Plane P, Plane ABC Plane BGF, plane CHE, Plane FED, Plane BCH